Rolling electronic length measuring device

ABSTRACT

An electronic measuring device is disclosed which includes a pair of wheels connected to an axle that passes through a drive gear. The drive gear is enmeshed to a second gear which, in turn, is coaxially connected to an encoder disk. The encoder disk has spaced-apart fins around its outer periphery. As the wheels turn and the encoder disk rotates, the fins and openings between the fins pass between an emitter and a receiver. The emitter and receiver are linked to a controller which calculates the distance traversed by the wheels based upon the number of fins that pass between the emitter and receiver, or with an active counting system (ACS). The controller also includes functions to establish start and stop points for a measurement and an easy means for dividing a measured distance into equal parts or segments and a means for marking the boundary points that define the segments when the measuring device is rolled back across the measured distance. The device can be used on both planar and non-planar surfaces.

TECHNICAL FIELD

This disclosure relates generally to measuring devices, such asmeasuring tapes. However, the disclosed device is an electronicmeasuring device that rolls along the surface to be measured.Accordingly, the device is suitable for non-planar surfaces includingcurved surfaces. The disclosed device provides an alternative tometallic coiled tape measuring devices, cloth or plastic measuring tapesand sonic or laser measuring devices.

BACKGROUND OF THE RELATED ART

One problem associated with conventional measuring devices such as tapemeasures, rulers, yard sticks or even sonic or laser type electronicdevices is that certain measurements are difficult to obtain.Specifically, accurately measuring the length of a curved or non-planarsurface with a metal tape measure is difficult. Further, cloth or fabrictape measures similar to the ones used by tailors are not convenient incertain environments, such as construction sites because they are noteasily retracted to a coiled position like the common metal tapemeasures. Electronic devices relying upon sonic or laser technology tomeasure distances are only suitable for straight measurements orline-of-site measurements.

Another problem associated with currently available length or distancemeasuring devices is that the manipulation of the obtained measurementmust be performed by the user with or without the use of a separatecalculator. For example, if a measured distance needs to be divided intoa number of equal segments, the user of a conventional tape measure mustfirst make the measurement, record the length, perform the requireddivision and then, using the tape measure, mark off the desiredsegments. This process is cumbersome and tedious and often results inerrors. Errors in such measurements the fields in carpentry or homeremodeling can be costly or damaging particularly if one or more holesare drilled in a wall or surface at one or more incorrect locations.

While traditional tape measures with a coiled measuring tape have beencombined with calculators, these devices have not been commerciallysuccessful because they fail to address the problem of measuring thedistance of a non-planar or irregular surface such as a curved wall.Further, the known combination calculator/tape measure devices merelycombine a calculator with a tape measure and do not provide the userwith any convenient means for dividing a measured distance into equallengths or segments and accurately marking those segments.

Accordingly, there is a need for an improved measuring device that canaccurately measure the length of a surface that is non-planar and thatfurther can easily and conveniently divide the measured length into oneor more equal segments and provide the user with a quick and easy systemto mark off the equal segments.

SUMMARY OF THE DISCLOSURE

An improved electronic measuring device is disclosed which can measurethe length or distance along almost any surface, including both planarand non-planar surfaces. In an embodiment, one disclosed devicecomprises at least one wheel for engaging or rolling along the surfaceto be measured. The wheel is mounted on an axle. The axle is coupled,either directly or indirectly, to an encoder disk so that rotation ofthe wheel results in rotation of the encoder disk.

In one embodiment, the encoder disk comprises a plurality ofcircumferentially spaced-apart opaque sections disposed betweentranslucent sections. The opaque and translucent sections (or the outerperiphery of the encoder disk) pass between an emitter and at least onereceiver as the encoder disk and wheel rotate. The emitter andreceiver(s) are linked to a controller. The controller computes thelength or distance traveled by the wheel based upon the number of opaquesections (or translucent sections) that pass between the emitter andreceiver during rotation of the wheel.

The encoder disk may be provided in a variety of forms. For example, theopaque sections may be fins and the translucent sections may be gaps oropenings between the fins. The encoder disk may be optically clear withspaced apart-opaque markings along its outer periphery that serve aslight-blocking sections with gaps or spaces of clear material disposedbetween the opaque markings. As another example, the encoder disk may bemade from an opaque material with though-holes disposed about its outerperiphery that allow light to pass through to the receiver(s) and theopaque material between the through-holes serves the purposed ofblocking light like the opaque sections or fins discussed above.

In a refinement, the axle passes through and is connected to a firstgear. The first gear is enmeshed with a second gear. The second gear iscoaxially connected to the encoder disk. In this embodiment, rotation ofthe wheel causes rotation of the axle thereby imparting rotation to thefirst gear, second gear and encoder disk.

Alternatively, the axle may be directly coupled to the encoder diskwithout a gear train coupling the axle to the encoder disk. If a geartrain is utilized, to prevent backlash when the directional movement ofthe device is quickly reversed, the axle or shaft supporting the secondgear and encoder disk may be loosely supported in a bearing and biasedtowards the first gear using a spring.

In a refinement, the at least one wheel comprises two wheels coaxiallyconnected together by the axle with the first gear disposed between thetwo wheels and mounted on the axle. By using two wheels, it is easierfor the user to roll the measuring device along a straight line.

In another refinement, the device comprises a display, such as a liquidcrystal display (LCD) or other type of display linked to the controllerfor displaying the distance traveled by the measuring wheel as computedby the controller.

In another refinement, the device further comprises a lower basestructure connected to an upper housing. The base has openings for theone or more wheels that roll along the surface to be measured. The baseis also connected to at least one bearing for rotatably supporting theaxle and at least one bearing for rotatably supporting the second gearand encoder disk. Of course, the bearings may also be connected to theupper housing. Also, the bearings may be molded as an integral part ofeither the upper housing or base.

In another refinement, the emitter and receiver are both mounted to afirst printed circuit board (PCB). The first PCB is linked to a secondPCB that is connected to and supports the controller and LCD.

Further, the second PCB may be linked to a plurality of control buttons.Each control button extending upward through openings disposed in theupper housing is linked to the controller to activate a program functionof the controller.

In another refinement, at least one of the control buttons is used toactivate a computation by the controller to account for the width of thehousing or the width of the measuring device.

In another refinement, at least one of the buttons is used to activate acomputation by the controller to divide the length previously measuredinto a plurality of equal segments. The segments may be defined by a“point” between adjacent segments. In such a refinement, as the deviceis rolled back across the previously measured distanced, the controllerprovides an indication when the device is approaching and traversing a“point.”

In another refinement, the segments are numbered and the number of thesegment being traversed is indicated on the display as the device ismoved back across the previously measured length. Further, in such arefinement, the display indicates when the device is approaching thenext segment so as to provide an early warning to the user as to howclose the device is to the next segment so that the user can be ready toplace a mark or other indicia on the surface at the designated “point.”

Further, the housing of the device may comprise two opposite side wallsthat are generally parallel to the axle that supports the one or morewheels. In an embodiment, each side wall is slidably connected to an endstop. Each end stop structure comprises a lower distal end having atapered point. Each end stop is movable between one or more lowerpositions where the tapered point can make an indentation or a markingon the surface being measured and an upper position where the taperedpoints are disposed above the surface being measured and therefore outof the way. It may also be preferable for the end stops to have a rangeof motion that extends below the surface being measures (or below thewheel or wheels that roll along the surface being measured) so that theend stop can be used to start a measurement at an end of a board orother structure.

Preferably, the end stops are biased into the upper position and arepressed downward by overcoming the bias to press the tapered pointagainst the surface being measured to mark one of the calculated“points” as discussed above or beginning and an ending points of ameasurement.

Also, each tapered point is preferably in vertical alignment with theouter surface of its respective side wall of the housing so that thetapered points can be accurately used to define the width of the housingwhich, in turn, can be easily accommodated for by the controller whenmaking a measurement. Further, in a preferred embodiment, when an endstop is extended downward beyond the surface being measured (i.e. pastthe wheels), the inside surface of the end stop is in vertical alignmentwith the outer surface of its respective side wall of the housing so theinside surface of the end stop can be used as an accurate start or stoppoint of a measurement.

For example, the user can press a control button to indicate to thecontroller which side wall of the housing is serving as a starting pointfor the measurement. After the device has been rolled across the surfaceto be measured, the user then may press a button to indicate to thecontroller which side of the device serves as the end point for themeasurement. If different side walls or sides of the device serve as thestarting or end points, the controller can easily accommodate for the“width” of the upper housing of the device by adding the width of thehousing to the computed length thereby providing for an accuratemeasurement.

Of course, there will be times when the width of the housing needs to besubtracted from the computed length or not taken into consideration atall.

In another refinement, the device includes a pair of guide rollers forstabilizing the device thereby providing a pair of measuring wheels anda pair of guide rollers.

In another refinement, the opaque and translucent sections of theencoder disk each have a uniform width and the receiver is a dualreceiver that comprises two spaced-apart receiving elements. Thereceiving elements are spaced-apart by a distance less than the uniformwidth of the translucent and/or opaque sections which thereby enablesthe controller to determine the direction of travel of the encoder diskand therefore the direction of travel of the measuring device.Preferably, the emitter is a light emitting diode (LED).

An improved method for measuring a length or a distance along a worksurface that may be planar or non-planar is also disclosed. The methodcomprises rolling a wheel of a measuring device as described above alongthe length or distance to be measured, computing the length or distancetraveled by the wheel by counting the number of opaque or translucentsections that pass between the emitter and the receiver as the wheel isrolled along the length or distance and determining a direction oftravel of the encoder disk and therefore the wheel by the order in whichthe receiving elements are shielded from light emitted by the emitter bythe passing opaque sections of the rotating encoder disk.

In a refinement, the method may also accommodate for the width of themeasuring device and the method may also include the option of dividingthe measured length into equal segments and enabling the user to retracethe length and easily mark off the equal segments at predetermined“points.”

Other features and advantages of the disclosed is devices and methodswill be apparent to those of ordinary skill in the art in view of thedetailed description provided below which is made with reference to theattached drawings provided in illustration of one preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective view of a measuring device made inaccordance with this disclosure;

FIG. 2 is an end view of the device shown in FIG. 1 with one of the endstops in a first lower position thereby enabling the tapered point toengage the surface being measured to provide a mark on the surface inalignment with the outermost surface of the side wall of the device;

FIG. 3 is another end view of the measuring device shown in FIGS. 1 and2 with one of the end stops in an second fully lowered position with aninner wall of the end stop being disposed below the surface beingmeasured and with the inner surface of the end stop being in alignmentwith an outermost surface of the side wall of the device therebyproviding a starting point or an end point for the length or distancebeing measured;

FIG. 4 is a partial sectional view of the device shown in FIGS. 1–3illustrating the slidable connection between the end stop and thehousing of the measuring device while the end stop is in its upper orretracted position;

FIGS. 5–7 provide an exploded view of the disclosed measuring devicewith FIG. 5 being a perspective view of the upper housing of themeasuring device shown in FIGS. 1–3;

FIG. 6 is a perspective view of the controller, control panel or controlbutton panel and a PCB of a disclosed measuring device;

FIG. 7 is a perspective view of the base structure, measuring wheels androtating components of a disclosed measuring;

FIG. 8A is an enlarged view of the components supported by the base asshown in FIG. 7;

FIG. 8B is an enlarged partial view of the emitter, receiver and encoderwheel components shown in FIG. 8A;

FIGS. 8C–8E are plan views of encoder disk designs that may beincorporated into the measuring device disclosed herein;

FIG. 9 is an illustration of the LCD of the disclosed device and a tableindicating which indicia will be disclosed on the LCD as the deviceapproaches and passes a “point” dividing equal segments of the measureddistance as computed by the controller at the command of the user;

FIG. 10 is a partial logic flow chart of the software stored on thecontroller shown in FIG. 6; and

FIG. 11 is another partial logic flow chart for the software stored onthe controller shown in FIG. 6.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

FIG. 1 illustrates a measuring device 20 that includes an upper housing21 with an opening 22 for a display 23, preferably a LCD. The housing 21also includes a plurality of openings providing the user with access tocontrol buttons 24, 25, 26, 27 and 28. Further, the device 20 alsoincludes end stops 31, 32 disposed in side walls 33, 34 respectively forproviding convenient start and stop points for a measurement and formarking the surface being measured as described in greater detail below.

Turning to FIG. 2, the rolling device 20 includes a measuring wheel 35(in this case a pair of measuring wheels 35 as shown in FIG. 7) thatengages the surface to be measured. In a preferred embodiment, a pair ofguide rollers shown at 36 is also provided. Preferably, two wheels 35are utilized as the use of two wheels 35 makes it easier for the user toroll the device 20 in a straight line.

In FIG. 2, the end stop 31 has been pushed downward, overcoming the biasof a spring (See 47 in FIG. 4) so that a tapered point 37 disposed at alower distal end 38 of the end stop 31 engages the surface 39 beingmeasured. In the “first” lower position shown in FIG. 2 (or “second”lower position shown FIG. 3 and discussed below), the end stop 31 can beused as either a start or a stop point for a measurement. The taperedpoint can also be used to make an indentation in the surface 39 and isparticularly useful for sheet rock, drywall and wood.

In FIG. 3, the end stop 31 has been lowered to the end if its range asdiscussed below with respect to FIG. 4 so that an inner surface 41 ofthe end stop 31 engages an end wall 42 of the surface 39 being measured.In both FIGS. 2 and 3, the end stop 31 (and the same applies for the endstop 32) serves as an accurate starting or finishing for a measurement.Specifically, in the “first” lower position shown in FIG. 2, the taperedpoint 37 is in vertical alignment with an outermost portion of the sidewall 33 of the upper housing 21. Thus, in the position in FIG. 2, thetapered point 37 can serve as a convenient start or finishing point forthe measurement. Similarly, in “second” or “lowermost” position shown inFIG. 3, the inner surface 41 of the end stop 31 is also in verticalalignment with an outermost portion of the sidewall 33 thereby alsoserving as a convenient starting or stopping point for a measurement.

The end stop 31 is shown in greater detail in FIG. 4. Specifically, theend stop 31 includes an upper thumb or finger grip 44 connected to avertical wall 45 that terminates in the distal end 38 which features thetapered point 37. The end stop 31 is biased into an upper position shownin FIG. 4 by the spring 47. The vertical portion 45 of the end stop 31is connected to opposing side walls, one of which is shown at 46. Eachside wall 46 of each end stop 31 (and 32) is connected to two pawlsshown at 49 and 51. The pawls 49, 51 each ride in elongated slots 52, 53respectively that are disposed in the vertical wall shown at 54 in FIG.4.

In FIG. 4, the end stop 31 shown in its upper or retracted positionunder the bias of the spring 47. The pawls 49, 51 are disposed at theupper ends 52 a, 53 a of the slots 52, 53 respectively. In first lowerposition shown in FIG. 2, the pawls 49, 51 are between the upper (52 a,53 a) and lower (52 b, 53 b) ends their respective slots 52, 53 and theorientation of the slots 52, 53 in the wall 54 maintain the taperedpoint 37 in vertical alignment with an outermost portion of the sidewall33 so that the mark or indentation made by the point 37 on the surface39 is accurately aligned with the sidewall 33 of the device 20.

As the end stop 31 is pushed further downward towards the fully extendedposition shown in FIG. 3, the inner surface 41 of the end stop 31, inturn, moves into vertical alignment with an outermost portion of theside wall 33 as shown in FIG. 3 when the pawls 49, 51 are disposed atthe lower ends 52 b, 53 b of their respective slots 52, 53. The slots52, 53 are disposed within a wall structure shown at 54 that may beformed from the base 50 as shown in FIG. 7 or which may be a moldedportion of the upper housing 21 or a separate component altogether. Asshown in FIGS. 7 and 8, each end stop 31, 32 includes a pair ofsidewalls 46 and two sets of pawls 49, 51 and the base 50 or housing 21provides two pairs of slots 52, 53 for each end stop 31, 32.

Turning to FIGS. 5–7, the upper housing 21 serves as an enclosure for aPCB 55 which is connected to and supports the button pad 56, controller57 and LCD 23. The PCB 55 is connected electrically to another PCB 58which is mounted to the base 50. The PCB 58 is connected to and supportsthe emitter 59 and dual receiver 61. The emitter 59 directs lighttowards the receiver 61. Preferably, for reasons discussed below, thereceiver 61 is a dual receiver with two separate receiving elements.

Referring to FIGS. 7 and 8A–8E, a finned encoder disk or wheel 62rotates between the emitter 59 and the receiver 61. The encoder disk 62as shown in FIGS. 7, 8A and 8C includes a plurality of fins or markers63 that are spaced apart with uniform gaps or openings 64 disposedbetween the fins 63. The encoder disk 62 also includes a hub 70 whichaccepts an axle 78 (see FIGS. 8C–8E) for coaxially connecting the disk62 to the gear 65 (see FIG. 8A).

The gaps or openings 64 of the disk 62 (FIG. 8C) may also be in the formof circumferentially spaced-apart through-holes 64 a as shown in thedisk 62 a of FIG. 8D. Still referring to FIG. 8D, the solid material 63a disposed between such through-holes 64 a serve the function ofblocking light like the fins 63 as shown in FIGS. 7, 8A and 8C. Anotheralternative is shown in FIG. 8E where the disk 62 b is made of anoptically clear material with circumferentially spaced-apart opaquemarkings 63 b disposed between clear light transmitting openings 64 b.In generally, the encoder disk 62 includes a plurality ofcircumferentially space-apart opaque sections 63, 63 a, 63 b disposedbetween a plurality of circumferentially spaced-apart translucent ortransparent sections 64, 64 a, 64 b. Other encoder disk 62 designs willbe apparent to those skilled in the art.

In the embodiment shown in FIGS. 7 and 8A, the encoder disk 62 iscoaxially connected to a splined shaft or gear 65 by the axle 78 (seeFIGS. 8C–8E). The gear 65 is enmeshed with a drive gear 66 mounted onthe axle 67. The axle 78 passing through the encoder disk 62 and gear 65is supported at either end (not shown) by the bearings shown at 68 a, 68b. Preferably, the bearing 68 b has an elliptical or non-circular holefor loosely accommodating and supporting the axle 78 so that one end ofthe axle 78 can move in an limited manner against the bias of the spring71 to prevent backlash when the direction of the travel of the device 20is quickly reversed.

Thus, to maintain a proper coupling between the gears 65 and 66, thespring 71 may be used to bias the gear 65 towards the drive gear 66.Again, it will be noted that the encoder disk 62 can be directly coupledto or mounted on the axle 67. The disclosed gear train 66, 65 has beenemployed to conserve space within the housing 21.

Preferably, the device 20 is battery operated and a battery housing isshown at 72. A plurality of support posts are shown at 73 and are usedto receive a screw from the underside of the base 50 to connect to base50 to the upper housing 21. The PCB 55 may be secured to the undersideof the upper housing 21 or may be mounted to the base member 50. In anyevent, the PCB 55 is electrically linked to PCB 58 or separately linkedto the emitter 59 and receiver 61.

Therefore, as the device 20 is rolled across the surface 39 to bemeasured, the wheels 35 roll across the surface 39. The wheels 35 arepreferably coated with rubber, thermoplastic rubber, or another similarmaterial. As the wheels 35 rotate, the drive gear 66 rotates and, inturn, rotates the gear or splined shaft 65 which, in turn, rotates theencoder disk 62. When the device 20 has been turned on, light is emittedfrom the emitter 59 and directed towards the receiver 61. Preferably,the receiver 61 includes a pair of receiving elements. The controller 57counts the number of fins 63 (or openings 64) that pass between theemitter 59 and receiver 61 as the fins 63 block the transmission oflight between the emitter 59 and receiving elements disposed on thereceiver 61. By counting the number of fins 63 that pass between theemitter 59 and receiver 61 (or, by counting the number of openings 64that pass between the emitter 59 and receiver 61), the controller 57 cancompute the distance traveled by the wheels 35. Further, by using a dualreceiver 61 with two receiving elements 61 a, 61 b, the controller 57can determine which direction the device 20 is being moved by the orderin which light from the LED element 59 a is blocked from the spacedapart receiving elements 61 a, 61 b by the passing fins 63.

Further, the controller 57 of the device 20 can accommodate for thewidth of the device 20 or the distance between the side walls 33 and 34as follows. By pressing one of the buttons, in this example, the button24, the user indicates to the controller 57 that the side 33 with theend stop 31 of the device 20 is the active measuring side or edge. Atthe conclusion of the distance measurement, the user then may keep theside 33 as the active measuring side or, in the event, the device 20engages a vertical wall, the user may then press another button, such asthe button 25, to indicate to the controller 57 that the opposite side34 is now the active measuring side. The controller will then add thewidth of the device between the sides 33 and 34 to the length measured.

Further, the controller 57 is preferably programmed to divide themeasured distance into a number of equal segments or points. The button27 can be used for this purpose. In a preferred embodiment, if adistance is to be divided by four equal segments or four points, thebutton 27 is pressed four times. If the distance is to be divided by tenequal segments, the button 27 is pressed ten times. The button 28 mayused as a clear or zero button and the button 26 may be used as acombination start/stop button as well as a power-on button. Theconfiguration and function assignments of the buttons may vary greatlyand only one example is provided here. Thus, the controller 57 iscapable of performing various calculations.

Turning to FIG. 9, the display 23 is shown when the user has selectedthe “points divide” option by repeatedly depressing the button 27. Whenthe device 20 is in this mode, the display 23 will read POINTS at thebottom left. The size of the equal segments determines which arrows 75a–75 d or 76 a–76 d will be shown for each distance range away from thepoint. For equal segments that are greater than two inches the columnson the left of the chart 77 will be used, and for equal segments betweenone and two inched the columns on the right of the chart 77 will beused. The center of chart 77 shows the state of each arrow within thatrange on the left or right. “F” indicates that the element is flashingand “O” indicates it is off. If the device 20 is approaching the pointfrom the left, then the left arrows shown at 75 a–75 d will begin toflash as the device 20 moves closer to the point. If the device isapproaching from the right, then the right arrows shown at 76 a-76 dwill begin flashing as the device moves closer to the point. When thedevice 20 is within 0.06′ of the point, then all of the arrows 75 a–75d, 76 a–76 d will be turned off and the word POINT will flash inaddition to an optional audible tone. During the approach and on thepoint, the display 23 will also indicate which point the device is near.For example, you may be approaching “1 OF 3 POINTS”, whereas the POINTSwill be on display throughout points mode. The images, distances andmethod for indicating the approach of each point can vary greatly.

FIGS. 10 and 11 illustrate logic flow charts for software that may bestored in the memory of the controller 57. The flow chaff s and logicshown in FIGS. 10–11 and merely one example of the many types ofprograms that could be used. At 100, the user decides to take ameasurement using the device 20, which is turned off or in the powerdown mode as shown at 101 and the user presses the power on button 26 at102 to power up the device at 103. At 104, the LCD indicates the laststatus and units of measurement data. At 105, the controller 57indicates the current active measuring side, i.e., the left side 34 orthe right side 33 on the LCD 23. At this point, to begin a newmeasurement, the user may press the clear button 28 at 106 to clear thepreviously stored data at 107 to redisplay the cleared status at 104 andcurrent active edge at 105 as shown by the loop 106-107-104-105-106. At108, the user may then change the units of measurement at 108 bysimultaneously pressing and holding the buttons 24 and 25 down for fiveseconds whereby the controller enters the loop 108-109-104-105-108 asshown in FIG. 10. To use the left side 34 of the device 20 as the activemeasuring side and the controller determines at 111 if this would be achange from using the right side 33 as the active measuring side and, ifso, would subtract the width of the device at 112 and the display 23would indicate that the left side 34 is the active measuring side at113. Similarly, if the right side 33 is selected as the active measuringedge at 114 and the controller 57 determines that this would be a changeat 115, the controller 57 adds the width of the device to themeasurement at 116 and makes an appropriate indication on the display 23at 117. To begin counting, the user then presses the start/stop button26 again at 118 and, if the controller 57 determines that the device isnot already active at 119, the controller 57 changes the active countingsystem (ACS) to active at 120 to begin taking measurement data. If thesystem is in the active counting mode, the controller 57 then changesthe system to the inactive counting at 121.

Then, the controller again passes through the loop104-105-106-108-110-114-118 and, if the user is beginning to take aninitial measurement, the user will not press the points divide button 27at 122 but, instead, will begin rolling the device whereby thecontroller will detect movement of the wheels 35 by way of the mechanismdescribed in FIGS. 7 and 8 above to activate the ACS system. In anembodiment, the speed limit is 10 feet per second and the speed limit ischecked at 124 (and an error signal can be generated at 124 a) beforethe active status is confirmed at 125 and the measurement begins at 126and the controller 57 continuously displays the measurement data on thescreen 23 at 127 before the user stops the device at 128. Again,proceeding through the loop shown at 104-105-106-108, the user then maychange the active measuring edge of the device at either 110 or 114 toeither result in an addition or subtraction of the width of the device20. If no such change is made, and the measurement has been completed,the user may then press the points button 27 at 122.

Turning from 122 a at FIG. 10 to 122 a at FIG. 11, the controller 57confirms the active mode status of the device at 131 and, if the deviceis still in an active mode, the controller 57 will reject the pointsmode. The controller will then confirm that the measurement is less thanone inch at step 132 and, if it is, the controller 57 will reject thepoints mode if the measurement is more than one inch, the controller 57proceeds to 133 and initiates the display of a point number “1” on thedisplay 23 as the points button 27 has been pressed only once. Repeatedpressing of the points button 27 at 134 sends the system into the loop134-135-133-134 until the desired number of points or segments isarrived at. The box 135 indicates that the maximum number of allowablepoints is 10 but those of ordinary skill in the art will realize thatthis number is flexible and will depend upon the particular applicationthat the device 20 is intended for. That is, more or fewer than tenpoints may be desired.

When the desired number of points or segments are entered, the userpresses the start/stop button 26 at 136 which initiates the dynamicmeasurement and the arrow display at 137 that is illustrated anddiscussed above at FIG. 9. At this point, to mark off the points alongthe path just measured, the user does not roll the device forward atstep 138 but, instead, begins to roll the device backward at step 142retracing the path just measured. Continued forward movement of thedevice at 138 will result in a continued display of the measurement dataat step 140.

To reach a target point by rolling the device 20 backwards as shown atstep 141, the controller 57 continually checks to make sure that thedevice has not rolled backward past the zero point at 142 (where if thedevice has rolled past the zero point, the display continues to indicatea zero value at 143), and assuming two minutes of an action have nottaken place at 144, and assuming the user has not pressed clear at 145,the bar graph (or arrows display) will indicate proximity to the firsttarget point and when it is reached at 141, optionally, an audio signalis produced at 146 and the icon point number flashes on the screen at147. As the user continues to move the device 20 backwards retracing thejust-measured path, and leaves a target point at 148, the target pointicon stops blinking at 149 and the loop137-138-142-144-145-141-146-147-148-149 is repeated for the next targetpoint. When the device rolls back to the initial starting point andbegins to exceed the “0” point, the measurement is complete andeventually two minutes of an action will occur and the logic returns todata FIG. 10 at step 151 or 152. Pressing clear at step 153 will convertthe controller 57 to distance mode at 154 to begin a new measurement at155 returning to the logic flow illustrated in FIG. 10. Again, twominutes of no action (see step 156) will result in the display 23 beingturned off at 157.

Accordingly, an improved measuring device 20 is disclosed which canaccurately measure distances or lengths along planar or non-planarsurfaces easily and conveniently. The device 20 is highly accurate byway of its employment of the end stops 31, 32. The device 20 may easilydivide a measured length or distance or equal segments which may then beeasily marked with the end stops 31, 32, and both visual and audibleindications are provided when the device retraces a measure distance anddesignated points are approached and passed.

1. An electronic measuring device for measuring length or distance alonga surface, the device comprising: at least one wheel assembly forengaging and rolling on the surface; the wheel assembly comprising anencoder; the encoder comprising a plurality of circumferentiallyspaced-apart markers, the encoder passing between an emitter and areceiver when the wheel rotates; the emitter and receiver being linkedto a controller, the controller computing the length or distancetraveled by the wheel by counting the number of markers that passbetween the emitter and receiver, wherein the emitter and receiver areboth mounted to a first printed circuit board, the first printed circuitboard being linked to a second printed circuit board that is connectedto and supports the controller, wherein the second printed circuit boardis linked to a plurality of control bottons, wherein at least one of thebuttons operates to activate a computation by the controller to dividethe length or distance previously computed by the controller into aplurality of segments, and wherein as the device is rolled back acrossthe previously measured length or distance, the controller provides anindication when the device is traversing between one segment and asucceeding segment.
 2. The measuring device of claim 1 furthercomprising a display linked to the controller, wherein an indication isprovided on the display by numbering the segments and indicating whichnumbered segment the device is traversing at any time as the device isrolled across the measured length or distance a second time and thecontroller has divided the computed distance into a number of segments.3. The An electronic measuring device for measuring length or distancealong a surface, the device comprising: at least one wheel assembly forengaging and rolling on the surface; the wheel assembly comprising anencoder; the encoder comprising a plurality of circumferentiallyspaced-apart markers, the encoder passing between an emitter and areceiver when the wheel rotates; the emitter and receiver being linkedto a controller, the controller computing the length or distancetraveled by the wheel by counting the number of markers that passbetween the emitter and receiver, wherein the housing comprises twoopposite and generally parallel side walls that define a width of thedevice, each side wall being slidably connected to an end stop, and eachend stop comprising a marking element for marking the surface beingmeasured at a point in vertical alignment with the side wall of thehousing to which the end stop is connected.
 4. The measuring device ofclaim 3 wherein each end stop also comprises an inner surface that is inalignment wit the outer surface of its respective side wall when thedistal end of the end stop is moved to a position below or beyond thesurface being measured.
 5. An electronic measuring device for measuringlength or distance along a surface, the device comprising: at least onewheel for engaging and rolling on the surface; the wheel being coupledto an encoder disk; the encoder disk comprising a plurality of uniformspaced-apart circumferential opaque sections with uniform translucentsections disposed between said opaque sections: the encoder disk passingbetween an emitter and a receiver, the emitter emitting light towardsthe receiver that is blocked by the opaque sections but allowed to reachthe receiver by the translucent sections as the encoder disk rotates;the emitter and receiver being linked to a controller; the controllercomputing the length or distance traveled by the wheel by counting thenumber of opaque sections that pass between the emitter and receiver;the controller being linked to a display for displaying the distance anddirection traveled by the wheels and computed by the controller; ahousing having a plurality of openings therein, at least one openingframing the display and at least one other opening providing access to aplurality of control buttons, wherein at least one of the controlbuttons operates to activate a computation by the controller to divide alength or distance previously computed by the controller into aplurality of segments, wherein as the device is rolled back across thepreviously computed distance, the display indicates when the device istraversing between one segment and a next segment.
 6. The measuringdevice of claim 5 wherein an indication is provided on the display bynumbering the segments and indicating which numbered segment the deviceis traversing at any time as the device is rolled across the measureddistance a second time and the controller has divided the computeddistance into a number of segments.
 7. An electronic measuring devicefor measuring length or distance along a surface, comprising: at leastone wheel for engaging and rolling on the surface; the wheel beingcoupled to an encoder disk; the encoder disk comprising a plurality ofuniform spaced-apart circumferential opaque sections with uniformtranslucent sections disposed between said opaque sections; the encoderdisk passing between an emitter and a receiver, the emitter emittinglight towards the receiver that is blocked by the opaque sections, butallowed to reach the receiver by the translucent sections as the encoderdisk rotates; the emitter and receiver being linked to a controller; thecontroller computing the length or distanced traveled by the wheel bycounting the number of opaque sections that pass between the emitter andreceiver; the controller being linked to a display for displaying thedistance and direction traveled by the wheels and computed by thecontroller: an enclosing housing with two opposite and generallyparallel side walls, each side wall being slidably connected to an endstop, each end stop comprising a lower distal end having a markingelement that is in alignment with an outer surface of its respectiveside wall when the end stop has been moved to a position where themarking element is in engagement with the surfaced being measured; andeach end stop also comprising an inner surface that is in alignment withthe outer surface of its respective side wall when the distal end of theend stop is disposed below or beyond the surface being measured.
 8. Amethod for measuring a length of or a distance alone a work surface, themethod comprising: rolling a wheel of a measuring device alone thelength or distance to be measured, the wheel being coupled to anencoder, the encoder comprising a plurality of spaced-apartcircumferential markers with spaces between said markers, the markersand spaces being of an equal circumferential width, the markers andspaces between the markers of the encoder passing between an emitter anda receiver, the emitter emitting light directed to the receiver, thereceiver comprising two spaced apart receiving elements, computing thelength or distance traveled by the wheel by counting the number ofmarkers that pass between the emitter and the receiver as the wheel isrolled along the length or distance being measured, determining adirection of travel of the encoder and therefore the wheel by the orderin which the receiving elements are shielded from the light emitted bythe emitter by the passing markers of the encoder, accounting for awidth of a housing that encloses the encoder; and dividing the measuredlength into a number of equal segments, and assigning numbers to thesegments.